The next twelve month period will be spent attempting to isolate and characterize the receptor protein for L-Gamma-carboxyglutamic acid. Initial studies have demonstrated the chemotactic response of peripheral mononuclear cells to this particular amino acid. The response is stereospecific and is optimum at a molar concentration of 10 to the -10. To our surprise L-glutamic acid does not evoke a chemotactic response in monocytes. However, preliminary studies with kainic acid, a heterocyclic amalogue of glutamic acid, does evoke a chemotactic response in monocytes. Furthermore the response is blocked in competitive studies with L-glutamic acid. In additional experiments the chemotactic response to L-gla in competively inhibited by equimolar concentrations of kainic acid. These findings suggest that L-gla L-glu and kainic acid bind to the same receptor protein on the mononuclear cells, but only L-gla and kainic acid evoke the chemotactic response. Our studies on the isolation and characterization of Alpha 2HS glycoprotein receptor will continue as described in the original grant proposal. We are currently raising polyclonal antibodies to purified Alpha 2HS in rabbits. The antibodies should allow further characterization of the receptor protein. In addition to the studies described above, we are currently embarking on the morphological studies described in the original research proposal on the influence of the bone associated macromolecules on the phenotypic expression of the osteoclast. Preliminary studies have been started using several cell lines, U937 and J774A1, which under appropriate conditions express a monocyte phenotype. The methodology for this work has been described in detail in the original proposal.